GREELEY — The spreading fungus that attacks and kills hibernating bats — now on Colorado’s doorstep — is expected to trigger an explosion of flies, beetles, moths and mosquitoes.

Bats play an unseen role as the nation’s main predator of night-flying insects, devouring billions every night.

White-Nose Syndrome fungus has killed more than 1 million bats east of Colorado.

If it reaches Colorado, insect populations will multiply unchecked, said Rick Adams, a biologist at the University of Northern Colorado and a bat expert who will host international discussions on the problem this month in Denver.

“You’re going to feel the effects of this,” Adams said. “You’re going to get bitten by a lot more other things that are actually likely to bite you, like mosquitoes.

“If you are a farmer, it’s going to cost you a lot more for pesticides to protect your crops,” he said.

The fungus, of unknown origin, attacks bats through the skin on their mouth and nose and prevents them from sleeping. Aroused out of hibernation, which they need from November to April, afflicted bats dart out of caves seeking food, burn up body-fat reserves, then freeze or starve.

Federal authorities say they won’t know until spring whether the fungus has infected any of the estimated 2 million bats in Colorado (representing 21 species, 15 of which hibernate).

The fungus leapfrogged from New York, where biologists identified it in 2006, reaching bats in western Oklahoma this past summer. Bat deaths have accelerated since 2009.

Trying to buy time for researchers to find a solution, Denver-based U.S. Forest Service officials have ordered the closure to visitors of hundreds of caves and 30,000 abandoned mines in Colorado, Wyoming, Kansas, Nebraska and South Dakota.

Scientists aren’t certain but suspect that the increasingly popular recreational exploration of caves might have led to people transporting the fungus on their clothing and gear.

“The threat of White-Nose Syndrome to the bat populations in this region is on our doorstep,” said Tony Dixon, the Forest Service’s acting regional director. “With White- Nose Syndrome killing from 80 to 100 percent of infected populations, the ecological consequences are too severe to risk the human spread of this deadly disease.”

U.S. Geological Survey and university biologists have launched a network of bat working groups.

Combating the fungus will be a focus at the North American Symposium on Bat Research that Adams and UNC are hosting Oct. 27-30 in Denver. Some contend Congress must free up more funds.

Boston University ecologist Thomas Kunz, who testified to Congress last year and will attend the symposium, recently calculated that bat deaths have left at least 492 tons of insects uneaten.

The exact consequences are unclear, with other forces affecting both bats and insects, Kunz said.

A study Kunz did in Texas in a cotton- and corn-growing area, which had a bat population estimated at 1.5 million, found the demise of the bats would cost farmers $750,000 to $1.2 million more each year for application of additional pesticides.

Fighting the fungus with fungicides appears unlikely, Kunz said, because reaching the bats and penetrating their fur would be difficult — let alone applying any fungicide frequently. Fungicides also could kill other species.

“The only thing that could be done — it’s going to take manpower and money — is to develop a vaccine to protect survivors,” Kunz said. “Inject them with some kind of vaccine. That’s years away. We’re likely going to end up with large numbers of bats dying.”

Extinction of some species “is possible,” he said.

No evidence has emerged that the fungus can harm humans.

Adams, who is author of “Bats of the Rocky Mountain West,” conducts studies using captive bats, with field work in the mountains and South Africa.

Adams founded the Colorado Bat Society and has pushed state mining overseers and mining-company executives to clean up and close abandoned mines using grated gates — not boards — so that bats can fly in and out of gaps.

He also has initiated collection of baseline data on insect populations along Colorado’s Front Range to enable comparative studies while monitoring the survival of bats.

Colorado’s bat population already is stressed by drought, warming temperatures and residential and commercial development. Bats survive in greatest numbers in Front Range foothills and west of Interstate 25. This time of year, they migrate into mountain caves and cliffs near treeline.

“There’s probably no way to stop the fungus,” Adams said. “It is so aggressive, moving so fast, that it’s probably going to run its course.”

And if bats here begin dying, “you’re not going to be sitting outside at night,” he said. “Insects are going to be getting into everything.”

Bruce Finley covers environment issues, the land air and water struggles shaping Colorado and the West. Finley grew up in Colorado, graduated from Stanford, then earned masters degrees in international relations as a Fulbright scholar in Britain and in journalism at Northwestern. He is also a lawyer and previously handled international news with on-site reporting in 40 countries.

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